Variable underlap drum facsimile transmitting apparatus



Nov. 18, 1952 R. e. THOMPSON VARIABLE UNDERLAP DRUM FACSIMILE IRANSMI'ITING APPARATUS 3 Sheets-Sheet 1 Filed June 23, 1950 .RUSSELL a.momscw IRVENTQR mum? NOV. 18, 1952 2,618,702

VARIABLE UNDERLAP DRUM FACSIMILE TRANSMITTING APPARATUS Filed June 23,1950 RLG. THOMPSON 3 Sheets-Sheet 2 4 4 a Y u RUSSELL G. THOMPSON m an dA Vm B Nov. 18, 1952 RMG. THOMPSON 5 Sheets-Sheet 5 Filed June 25, 1950RUSSELL G. THOMPSON INVENTOR ATTORNEYS Patented Nov. 18, 1952 VARIABLEUNDERLAP DRUM FACSIMILE TRANSMITTING APPARATUS Russell G. Thompson,Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey Application June 23, 1950, Serial No. 169,992

Claims. 1

This invention relates to facsimile apparatus and more particularly tofacsimile transmitting apparatus adapted to scan picture sheets ofdifferent sizes.

In facsimile systems, the picture to be transmitted is generally wrappedaround the surface of a drum which is rotated past a scanning beam oflight. A suitably mounted photocell receives light reflected from thepicture and converts it into corresponding electric currents which areemployed to control a receiver apparatus. The clamping and other meansemployed for holding the picture on the drum pass the scanning beam onceeach revolution of the drum and, unless prevented from doing so, theresulting modulation of the light reflected to the photocell will causeundesirable markings along both margins of vthe recording medium.

Prior devices usually required the use' of picture sheets of a sizewhich would leave a predetermined underlap occupied by the clamping bar.A cam rotating with the drum was arranged in a position such that itwould function to disable the recorder during the time this underlap wasbeing scanned. Incidentally, this underlap period has generally beenutilized for the transmission of a synchronizing signal.

The present invention contemplates a transmission drum provided withsheet-holding means adapted to accommodate sheets differing, withinlimits, in width. This results in different underlap periods duringwhich the recorder should print white i. e., not try to reproduce theunderlap. The fact that the sheets may also differ in length is of noconsequence to the present invention.

,An object of the invention is to provide a facsimile transmitter whichwill accommodate pictures of different sizes and which will not transmitsignals corresponding to the scanning values of the underlap. Anotherobject of the invention is the provision of means adjustable with themanipulation of the sheet securing means for transmitting white duringthe underlap period as determined by the width of the sheet secured onthe transmitting drum.

Another object of the invention is the provision of a commutatorrotatable with a facsimile drum for completing a circuit during the timethe underlap is passing the scanning light and adjustable with a bailwhich holds one edge of a picture sheet on the drum.

Other objects and advantages of the invention willbe apparent from thefollowing detailed description when read in connection with theaccompanying drawings in which:

Fig. 1 is a partial view in perspective of a facsimil apparatusembodying the preferred form of the invention;

Fig. 2 is a plan view of the clutch actuating mechanism shown in Fig. 1;

Fig. 3 is a sectional end view of certain parts of the actuating meansfor the clutch and bail latch shown in Fig. 1;

Figs. 4 and 5 are end and plan views, respectively, of the mountingmeans for the paper bail shown in Fig. 1;

Figs. 6, '7 and 8 are sectional views of details of the clamping barshown in Fig. 1;

Figs. 9 and 10 are front and end views, partly in section, showing theconstruction of the adjustable commutator on the apparatus shown in Fig.1;

Fig. 11 is a front view schematically showing the operating parts of acomplete facsimile apparatus; and

Fig. 12 shows schematically an alternative embodiment of the invention.

In accordance with the preferred embodiment of the invention, tworelatively movable commutator segments are carried by the shaft of thetransmitter drum. One of these segments is fixed to the shaft with itstrailing edge in a definite position with respect to the trailing edgeof the clamp bar which holds one edge of the sheet on the drum. Theother segment is rotatable on the shaft and carried by a paper wrappingroller or bail with its leading edge fixed in a definite position withrespect to the leading edge of the bail. Thus the angular overlap of thecommutator segments corresponds to the angle subtended by the underlapof the sheet on the drum and these segments are utilized to complete acircuit so that white will be recorded while the underlap is passing thescanning beam.

More particularly, there are shown in Fig. 1 parts of a facsimileapparatus including a transmitting drum [0 and a recording drum IIhaving'a common shaft l2. The recording drum II is shown provided with ahelical ridge l3 scanning element but any other well known recorder maybe employed since the recorder per se forms no part of the presentinvention. The shaft I2 is adapted to be driven by a suitable motor l4through a worm IS, a worm gear 16 and two clutch members I! and 18. Themember I1 is carried by the worm gear l6 and contains a clutch socketwhile the member l8 which has a clutch cone is keyed to but free to movelongitudinally of 3 the shaft |2. The clutch socket member l1 and theworm gear |6 are freely rotatable on the shaft l2 but are restrainedfrom longitudinal movement by any suitable means such as a collar l9held in place by a set screw 29.

A clutch lever 2| pivoted at 22 to the frame 23 of the apparatus has anear 24 provided with a pin 25 extending into a circumferential grooveformed in the clutch cone member l8. A compressed spring 26 between theclutch cone member l8 and a collar 21 secured to the shaft I2 by a setscrew 28 serves to bias the clutch cone member |8 to clutch engagingposition. A cam 29, when rotated clockwise by a handle 39, 90 degreesfrom its position as shown in Fig. 1 will move the clutch lever 2| tothe right and thereby disengage the clutch members l1 and I8 to stoprotation of the shaft |2 while the worm gear I6 continues to be rotatedby the motor 4. Any other suitable clutch mechanism may of course beemployed. With the clutch members disengaged the shaft l2 may be readilyrotated by a hand wheel 3| for securing to the drum ID the picture to bereproduced.

With the handle 30 in the position shown in Figs. 1 and 2 the clutchlever 2| is in clutch engaging position and the riser on the cam 29elevates a follower 32 carried on one end of a lever 33 fulcrumed nearits middle on a boss 34 provided on a portion of the frame 23. The otherend of the cam follower lever 33 is connected through a link 35 to acrank arm 36 to control the angular position of a rod 31 extendingparallel to the drum l0 and carrying two latch arms 38. The follower 32is urged against the cam by a torsion spring 39 encircling the end ofthe rod 31 and with one end secured to the crank arm 36 and with theother end anchored to the frame 23. Thus, when the handle 30 is rotatedto disengage the clutch members l1 and H! the surface of the cam 29permits the spring 39 to rotate the rod 31 to bring the latch members 38into position to have their notches engaged by pins 48 extendinglongitudinally of bail plates 4| The bail plates 4| support a paper bail42 which may be provided with a number of spaced rubber rollers 43 forwrapping a document onto the drum I8 and for holding one edge of thedocument during a scanning operation.

As best shown in Figs. 4 and 5, the bail plates 4| have slotted openings44 which bear against the shaft |2 in one dimension but are larger thanthe shaft |2 in the dimension extending through the paper bail 42 sothat documents differing in thickness may pass between the bail 42 andthe drum ID. A spring 45 under tension between a bent-out ear 46 on thebail plate 4| and the bentout end of an arm 41 having its other endpivotally secured at 48 to the bail plate 4| performs the dual functionsof biasing the paper bail 42 against the surface of the drum H) and ofpressing a roller 49 carried by the arm 41 into engagement with adetent-wheel 59 secured to a reduced end 5| of the drum II]. By reasonof the spring pressed roller 49 engaging the detent wheel 50 the bailplate 4| can easily be rotated with respect to the drum I9 but will, inthe absence of an outside force, rotate with the drum ID. Acounterweight 52 is attached to the bail plate 4| for balancingpurposes.

As shown in Figs. 6 and 7 a clamping bar 53 extending longitudinally ofthe drum H] for securing one edge of a document or picture sheet to betransmitted is biased to closed position against a plate 54 by means ofa spring 55 under compression between the under surface of the plate 54and the head of a stud 56 extending through the plate 54 and secured tothe clamping bar 53 as by riveting. It will be understood that aplurality of similarly arranged biasing springs 55 are employed alongthe length of the clamping bar 53 as illustrated in Fig. 1. A cam shaft51 common to all the studs 56 has cam surfaces formed by grinding flatsin the shaft 51 to a depth such that there is clearance between the camsurface and the head of the stud 56 at its lowest limit of travel. Forthe reason next to be explained, this clearance permits a limitedrotation of the cam shaft 51 without moving the clamping bar 53.

Referring now to Figs. 6 and 8, it will be noted that the cam shaft 51has an additional flat against which a floating follower 58 is pressedby a spring 59 under compression between the plate 54 and the follower58. This cam flat is milled to a depth which is less than the radiusofthe shaft 51 so that the shaft 51 is stabilized in the position shownin Fig. 8, i. e., the shaft 51 is unstable in any other angular positionin which the face of the follower 58 is not tangent to the circularportion of the shaft 51. This stabilized position of the shaft 51 issuch that a bifurcated crank 69 secured to the end of the shaft 51 is inthe position shown in Fig. 4. The above-mentioned permissible limitedrotation of the cam shaft 51 allows the pins 62 to temporarily depressthe cranks 68. as the pins 62 move past.

In order to insert one end of a picture sheet 6| under the clamping bar53, the handle 38 is turned to disengage the clutch members l1 and H3and to allow the spring 39 to rotate the latch arms 38 into the path ofthe pins 49 (see Fig. 1). The hand wheel 3| is, rotated in the directionof the arrow, which is the direction of the scanning rotation, until thearms 38 engage and latch the pins 49 on the bail plates 4|. The handwheel 3| is now rotated in the opposite direction to rotate the drum |8relatively to the stationary bail 42 until the bifurcated ends of thecranks'68 receive pins 62 carried by the bail plates 4| and the cranks64 rotated, about 90 degrees, until lugs 63 on the cranks engage thereduced end portion 5| of the drum ID. This rotation of the cranks 60turns the cam shaft 51 to raise the clamp bar 53 to the position shownin Fig. 1 thereby permitting the edge of the sheet 6| to be insertedthereunder. Rotation of the handwheel 3| in the direction of scanning,releases the cranks 69 and the bar 53 clamps the edge of the sheet 6|.Continued turning of the handwheel 3| rotates the drum ll and the sheet6| under the paper bail 42 which wraps the sheet 6| smoothly on the druml8. After the drum H! has been turned so that the trailing edge of thesheet 6| to be scanned is adjacent the bail 42, the handle 39 isreturned to the clutch engaging position shown in Fig. 1 which releasesthe latches 38 so that the entire assembly of drum, clamp, sheet andpaper bail may rotate for a scanning operation.

A scanning unit 64 may be of any known structure for projecting a beamof light onto the sheet 6| and for deriving electric signalscorresponding to the light reflecting properties of successive elementalareas of the picture on the sheet 6|. The drum I9 is rotated at aconstant rate While the scanning unit 64 moves along the drum parallelto its axis in a well known manner.

The underlap which is that portion of the drum l9 between the paper bail42 and the trailing edge of the clamp bar 53 is different for picturesheets of different sizes and in order to assure in each case that thisunderlap is not reconducting strip 61 on the ring 65 is fixed in adefinite position with respect'to the leading edge of .the paper bail 42so that the strip 61 makes contact with its brush 68 just prior to theinstant the leading edge of the bail 42 enters the scanning beam. Theconducting strip 69 is positioned on the ring 66 so that its trailingedge leaves its associated brush ll just after the trailing edge of theclamp bar 53 has passed the scanning beam.

It is now apparent that the mounting of the sheet 6| on the drum lautomatically adjusts the slip rings 65 and 66 so that the angularoverlap of their conducting strips 61 and 69 corresponds to the anglesubtended by the underlap on the drum II. The conducting strips areelectrically connected as by a spring contact member 1| secured to thering 65 in contact with the strip 61 and extending into sliding contactwith an annular plate 12 of conducting material secured to the side ofthe ring 66 and in electrical contact with the conducting strip 69.

The operation of the commutator will now be described in connection withFig. 11 which shows schematically the relation between the overlap ofthe conducting strips 61 and 69, the underlap of the sheet 6| on thedrum N, the brushes 68 and 10, and the scanning unit 64. When intenselight is reflected by the sheet 6| onto a photocell I3 in the scanningunit 64, the cell 13 has maximum conduction and the signal passed by anamplifier 14 to the electromagnetic driver 15 for a printer bar I6 issuch as to hold the bar 16 up, i. e., it rints white. The printer bar 16and its driver 15 may be constructed as described in my copendingapplication Serial No. 12,077.

filed February 28, 1948.

During scanning the shaft I2 is rotated so that the front of the drum I6moves downward as viewed in Fig. 11. As here shown, the brushes 68 and10, the scanning unit 64, and the shaft, l2, are in a common plane sothat the leading edge of the commutator strip 61 is in line with theleading edge of the paper bail rollers 43 and the trailing edge of thecommutator strip 69 is in line with the trailing edge of the clamp bar53. Thus, from the time the leading edge of the rollers 43 enters thescanning beam until the trailing edge of the clamp bar 53 leaves thescanning beam, the two brushes 68 and II are both in. contact with theirrespective commutator f strips 61 and 69 which render the input circuittothe amplifier l4 conductive and, hence, the' bar 16 does not printregardless of whether or not light is reflected to the photocell l3.

1 An alternative arrangement is shown in Fig. 12

a disc TI of insulating material and a disc 18 of conducting materialmounted on the shaft 12 for axial movement but restrained fromrotational movement by a key 19. The two discs 11 and 18 are joinedtogether in a plane inclined to the axis of the shaft 12 whereby theangle of rotation through which both the brushes 68 and 70 make contactwith the conducting disc 18 depends upon the axial position of thecommutator. By securing to the bail plate 4| a face cam which isrotatable with the plate 4| on the shaft l2 the axial position of thecommutator will depend upon the position of the ball 42 with the resultthat the angle through which the two brushes 68 and 16 are shorted bythe conducting disc 18 will correspond to the angle subtended by theunderlap of the picture sheet on the drum H]. A spring BI is provided tourge the commutator .against the face cam 86. As before, thisarrangement can be employed to cause a white signal to betransmittedthroughout the interval the {underlap is being scanned.

While for the purpose of disclosing the invention only two specificembodiments have been described in detail, it will be evident to thoseskilled in the art that many other obvious embodiments may be devisedwithout departing from ,the invention, the scope of which is pointed outin the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a facsimile transmission apparatus, a rotatable drum forsupporting a picture sheet, means for securing picture sheets of varyingwidth to the surface of the drum comprising means mounted on the drumfor gripping the leading edge of the picture sheet and a paper bail forpressing the trailing edge of the picture sheet against the drum wherebythe underlap between the leading edge of the paper bail and the trailingedge of the gripping means varies in width according to the width of thepicture sheet, a scanning system for analyzing the picture sheet, and acommutator rotatable with the drum and adjustable by the movement of thepaper bail to the trailing edge of the picture sheet for completing acircuit only during the times the unde lap is being scanned.

2. The apparatus claimed in claim 1 wherein the commutator comprises twosemi-circular conducting segments electrically connected and spacedaxially on a rotatable shaft to which the drum is secured, one of saidsegments being fixed to the shaft and having an associated slidingcontact so positioned that upon rotation of the drum the trailing end ofsaid one segment leaves its contact at the time the trailing edge of thesheet gripping means passes the scanning system, the

other of said segments being rotatably mounted f on the shaft formovement with the paper bail and having an associated sliding contact sopositioned that upon rotation of the drum the leading end of said othersegment comes under its contact at the time the leading edge of thepaper bail enters the scanning system.

3. The apparatus claimed in claim 1 wherein the commutator comprises anaxially eccentric ring of conducting material having two axially spacedassociated sliding contacts and the movement of the paper bail producesrelative movement parallel to the axis of the drum between said ring andsaid sliding contacts.

4. In facsimile transmission apparatus. a rotatable picture sheetcarrying drum, a clamp bar extending longitudinally of the drum forgripping one edge of a picture sheet, a paper bail rotatable relativelyto'the drum for wrapping the picture sheet around thedrum, spring meansfor urging the paper bail toward the surface of the drum and forreleasably holding the paper bail in fixed position on the drum wherebythe other edge of the picture sheet is secured in position for ascanning operation, scanning means for deriving signals corresponding tothe light values of the picture sheet, and means adjustable by thewrapping movement of the paper bail to said other edge of the picturesheet for providing a signal corresponding to white whenever theunderlap portion of the drum is being scanned.

5. In facsimile transmission apparatus, a rotatable sheet supportingdrum, an output circuit, a scanning system for furnishing signals to theoutput circuit, means carried by and extending longitudinally along thedrum for holding one edge of a sheet, means extending longitudinallyalong and movable circumferentially of the drum to the opposite edge ofthe sheet for holding said opposite edge of the sheet whereby theangular separation of the two holding means is a function of the widthof the sheet, and means controlled by the movement of thecircumferentially movable means for furnishing a predetermined signal tothe output circuit while the underlap defined by the two holding meansis being scanned.

RUSSELL G. THOMPSON.

REFERENCES CITED The following references are of record in the

